Forum Moderators: skibum
The biggest factor may very well be the on page conversion when they get to the merchant - people know and trust amazon, and many already have accounts.
Shouldn't cost you too much in PPC to test it out.
Apples and oranges--you really can't compare that to Amazon. In my experience, in a book area, Amazon converts MUCH better than any other program. I would much rather get 5% of, say, $500 than 10% of $100. I used to belong to several bookstore programs in addition to Amazon, and I've dropped all of them but two specialty stores--and I saw my income go up when I did, and removed links that weren't doing anything but distracting people.
Try things out.